1. Field of the Invention
The present invention relates to an input/output (I/O) connector for a portable communications device. More specifically, the present invention discloses an I/O connector that requires less surface area on a circuit board.
2. Description of the Prior Art
I/O connectors are used in a wide variety of electronic devices to electrically connect different types of devices to each other. In particular, such connectors are found on portable communications devices, such as cellular telephones. They may perform a variety of functions, such as the connecting of the cellular telephone to a computer to establish a communications link, or the docking of the cellular telephone to a docking station for the recharging of batteries, etc.
I/O ports are traditionally mounted on a circuit board of the personal communications device, and protrude through the casing to establish an electrical connection between the circuitry on the circuit board and an external device. Please refer to FIG. 1. FIG. 1 is an exploded view diagram of a prior art cellular telephone 10. The cellular telephone 10 is a well-known portable personal communications device, and comprises a circuit board 12 set between an upper casing 14 and a lower casing 16. The circuit board 12 has a prior art I/O connector 20 electrically connected to other devices (not shown) disposed on the circuit board 12. Various methods are used to establish the electrical connection between the I/O connector 20 and the devices on the circuit board 12, which are discussed below. The I/O connector 20 has an external interface end 22 that is used to electrically connect to a corresponding I/O connector on a separate device (not shown). Besides comprising a plurality of electrical contacts 24 to establish electrical connections with the external device, the I/O connector 20 may also optionally comprise a locking mechanism 26 to establish a firm mechanical connection between the respective devices. In this manner the cellular telephone 10 will not become unintentionally unplugged from the external device. The upper and lower casings 14 and 16 each have an opening 18. When the upper and lower casings 14 and 16 are brought together, the circuit board 12 is held snugly between them and the external interface end 22 peeks through the opening 18 so that it can mate with its corresponding connector on the external device.
As noted above, a variety of methods can be used to electrically connect the I/O connector 20 to the other components on the circuit board 12. The most commonly used method is surface mounting technology (SMT). Please refer to FIG. 2, which is a diagram of the prior art I/O connector 20 mounted to the circuit board 12 using SMT. Protruding from the back end of the I/O connector 20 are a plurality of pins 21. Each pin 21 should have a corresponding contact 24 on the external interface end 22 of the I/O connector 20. Using SMT, the pins 21 are soldered to the circuit board 12 at predetermined soldering points 23. These soldering points 23 have traces (not shown) which lead away from the soldering points and electrically connect to other components on the circuit board 12. Using SMT, the I/O connector 20 is firmly fixed to the circuit board 12.
Alternatively, the I/O connector 20 may simply clamp onto the circuit board 12. This is depicted in FIG. 3. The circuit board 12 can have a variety of traces (not shown) on both its top and bottom surfaces. These traces lead up to the edge of the circuit board 12. The I/O connector 20 has a plurality of elastic contacts 25 that electrically connect to their corresponding contacts 24 on the external interface end 22. When the I/O connector 20 is slid onto the edge of the circuit board 12, the elastic contacts 25 make electrical contact with their respective traces, and also firmly hold the I/O connector 20 to the circuit board 12. When disposed within the upper and lower casings 14 and 16, the casings 14, 16 prevent the I/O connector 20 from sliding back off the circuit board 12 if it is pulled or jerked.
Another method used to connect the I/O connector 20 to the circuit board 12 is depicted in FIG. 4. The method is very similar to that discussed in FIG. 3. Traces (not shown) lead up to an edge of the circuit board 12. A plurality of elastic conductors 27, each connected to a corresponding contact (not shown) on the external interface end 22, make electrical contact with their respective traces. However, instead of clamping onto the circuit board 12, as is done in FIG. 3, the I/O connector 20 is held in place by the upper and lower casings 14 and 16, which both firmly press the I/O connector 20 against the circuit board 12 and also locks it into position.
All of the above prior art methods used to electrically connect the I/O connector 20 to the circuit board 12 require a significant amount of area on the circuit board 12 in comparison to the area of the I/O connector 20. That is, a large portion of the I/O connector 20 actually resides on the circuit board 12, taking up space. With the continuing trend of reducing the sizes of portable communications devices, the total size of the circuit board must also be reduced. This, however, is hampered by the area consumed on the circuit board 12 by the I/O connector 20. Hence, the prior art I/O connector 20 is inhibiting miniaturization trends in portable communications devices.
Additionally, a limited tolerance is permitted between the I/O connector 20 and its opening 18 in the casings 14 and 16. Small misalignments of the circuit board 12 in the casings 14, 16, or of the I/O connector 20 on the circuit board 12 can result in difficulty, or a complete failure, to mate the upper casing 14 with the lower casing 16. Consequently, the prior art method of mounting the I/O connector 20 onto the circuit board 12 exacerbates tolerance requirements, and complicates the manufacturing process of the cellular telephone 10.